Rotary pump



oct. 19,1948. yp, BARKER 2,451,603

Ronny Puur Filed oct. 4, 194.4l l 4 sheets-Shasta 'N .g5 k

.Trudel-don Ot. 19, 1948. v. D. BARKER ROTARY Puur 'Filed 9ct. 4. 1944 4 Sheets-Sheet 3 Patented ci. i9, 1948 ROTARY PUMP Virgil D. Barker, Westfield, N. J. Application October 4,-1944, Serial No. 557,075 claims. (orina- 130) in -such pumps the parts so covered with yieldable material have required a degree of clearance between the impelling member and the pump chamber sufficient to avoid excessive frictional resistance. They have thus been limited in their usefulness to larger and cruder installations where the losses due to leakage are small as compared with the volume of fluid handled.

It is an object of my invention to overcome this defect.

It is also an object of the invention to eliminate substantially all peripheral sliding contacts between the two displacing elements and between these elements and the pump housing, and to substitute therefor rolling vor other non-sliding contacts in order to minimize normal wear even in the presence of abrasively charged fluids.

' An additional object of the invention is to obtain these non-sliding contacts with members of yieldable material under such pressures as will effectively prevent leakage of iuids past the fluid displacing members.

A further object of the invention is to obtain continuous non-sliding contact between each of the two displacing elements and between these elements and the pump housing by enveloping the driving rotors or cams with bands of yieldable material,r the arrangement being such that lthe bands will not only yield appreciably in compression against each other and against the pump housing but will also, by yielding in bending, maintain their conformity to the shape of the rotors While the rotors are rotating and while the bands are held, by contact of their peripheries with the pumpv housing, against instantaneous movement as a whole.

It is also an object o the invention to hold any particles of solid matter or abrasive material against any movement along the Wall or surface of the pump chamber while under pressure between the yieldable material and the wall.

It is also an object to provide a conjugate piston pump in which the periphery of the rotor element, may be generated by relatively simple automatic machinery.

It is a further object of the invention to produce a conjugate piston pump inwhich minor inaccuracies in the machining of cooperating parts will be effectively neutralizedv so as to be of no consequence in the efficiency of the pump.

Further objects o'f the invention, improvement in details of construction and economies of manufacture will more definitely appear from the following description.

In the claims and in the description, for convenience, `parts are often identified by specic names; thus the two conjugate impelling elements of the pump, including the enveloping bands, are called pistons; and the rotary elements within the enveloping bands are called rotors; and other parts are designated by various terms; but such nomenclature is intended to be as generic as the art to which the invention relates will warrant.

My invention is particularlydeiined in the appended claims, and the best form in which I have contemplated applying it is illustrated in the accompanying drawings, in which.

Fig. 1 is a vertical cross section of the pump "on une a-l of Fig. 2;

Fig. 2 is a vertical longitudinal section, partially in elevation, taken in general on line 2-2 of Fig. 1;

Fig. 3 is a plan view; Fig. 4 is an end elevation, viewed from the right side of Fig. 2; and

Fig. 5 is a sectional detail of a modified construction in which antifriction means 'is incorporated between the rotor and the exible band.

Referring to Fig. 1, the pump including a casing, designated asa whole by I, which incloses a pump chamber 2 that embraces two cylindrical portions 3, 4. Casing I includes an intermediate part 1 (see also Fig. 2) which provides the peripheral walls of the pump chamber, and which lhas an inlet 5 and an outlet 6. Part I is machined to present parallel faces, for the reception of cover plates 8 and 9. These cover plates, are secured to part I by bolts I0 which pass through the cover plates 8 and 9 and the intermediate part l. Cover plates 8 and 9 are bored concentrically of the cylindrical chamber portions 3 and 4 to receive shafts II and I2 which Carry rotary pistons, designated as a whole by K and L, respectively. The cover plates 8 and s are provided with packings and glands at I5, I5 and I, I6 to form seals about shafts II and I2, respectively. On opposite sides of the pump casa pulley or gear, not shown, the reduced portion" I 9 of driven shaft II being slotted at 20 for the reception of a key by whichvthe driving means is keyed to the shaft.

The support C with its antifriction bearings I1, I1 is similar in structure to support B and its bearings, except that both bearing caps are provided with bores, as in the case of cap D, for the accommodation of reduced portions 2|, 22 of shafts II and I2,ron which are secured gears 23, 24, which gear the shafts together for rotation in opposite directions. Gears 23 and 24 are enclosed in gear casing F.

The structure thus far ,described is such as may be applicable in conventional conjugate rotor pumps, the important feature of my invention in its preferred form being more particularly illustrated in Figs. 1 and 2.

My invention contemplates the utilization of a exble band, or bands, which roll without' each piston the rotor (I3 or I4) is in the form of a solid quasi-ellipse or double cam enveloped by a flexible band 26 of natural or synthetic rubber, plastics, or other suitable material, which,

while-adjacent the periphery of the rotor, is not flxed thereto, but is free and relatively movable.

Means for minimizing friction between the rotor (I3 or I4) and band 26 is provided, so that there may be movement of the rotor or cam over the inner surface of band 26, to press it outward against the wall (3 or 4) of the pump chamber, without carrying the band along with the rotor; and so that there is no sliding motion between the band and the wall of the pump chamber. Any desired means for minimizing friction between the rotor and band 26 may beA employed. As shown, a series of antifriction needle rollers 21 constitute an element of the antifriction means, which operate in the usual manner of needle roller bearings.

Fig. shows a modified construction in which X the flexible band 26 includes as a part thereof a spring steel facing 28 bonded to the rubber, the

The function of the needle rollers or other fricand thereby facilitate the non-sliding contact of the bands with the walls of the pump chamber. The rolling action of the bands is similar to the rolling action of a caterpillar tread, and the result is to produce instantaneously stationary contact between the peripheries of the bands and the arcuate walls of the pump chamber. In practice, the proportions of the rotors, needle rollers, bands and housings will be such as to produce considerable pressure at the points of contact between the bands and the chamber walls (3 or 4).

When the band, which is of yieldable material, is pressed against the chamber wall, it operates to arrest the motion of any abrasive material that may come between the band and the wall; and the band yieldingly envelops and holds the grains of such materialwithout motion relative tothe chamber wall. When the band separates from the chamber wall. the abrasive grains are released and pass on with the liquid, without having been ground against the Wall in a. deleterious manner.

The band 26 is of such length that no space intervenes between it'and the rotor (I3 or I4) except such as is occupied by the needle rollers 21 or other antifriction device. In many instances,

particularly where band 26 is of rubber and the needle rollers or other antifriction devices employed are of substantial mass, I prefer to have the band 26 under considerable stretch or tension. This tension serves to maintain the band and rollers in proper position against the action of centrifugal forces. Also it is well-known that rubber is much more resistant to fatigue under conditions of rapid variations in stress and that the internal energy loss resulting from rapid bending\will be greatly reduced, if the order of stress does not change too greatly and if the sign does not change; and if the band is under considerable initial stress, a change in stress is relatively less. In using a stretched rubber band 26, the optimum amount of stretch will vary with the use for which the pump is intended, the size and speed of rotation, the characteristics of the particular rubber used, etc. According to my experience, the desirable stretch or elongation may be from 25% to 150% of the unstretched length.

In operation, there is a crescent-shaped space 29 (Fig. 1) of appreciable volume between the band 26 and the wall of the chamber adjacent the minor axis of the piston (K or L), which will be occupied by the fluid passing through the pump. Functionally, the pump displaces fluid in substantially the same manner as any conjugate rotor type of pump. It will be seen that for each revolution of each piston (K or L) two crescent-shaped slugs of fluid typified by area 29, will be delivered toward the outlet 6, since the rolling contact of the pistons with each other, which extends from cover plate 8 to cover plate 9' along a line parallel with the axes of rotation of the pistons, prevents any return of fluid toward inlet port 5. And these slugs of fluid move around the chamber wall with substantially uniform velocity. With the form of piston (K or L) shown, the pulsations in the fluid delivery rate may be reduced to about 1% or even less.

There is the possibility of some leakage between the cover plates 8 and 8 and the end surfaces of the bands 26, 26. These bands are limited to relatively small radial and tangential movement relative to axes of shafts II and I2. Such'radial (I3 or I4).

movement is limited to the difference between the major and minor axes of rotary pistons K and L. Such tangential movement, because of rolling contact with the chamber wallis only a small fraction of the apparent peripheral movement of the pistons K and L. y Actually the bands will slowly progress angularly in a direction opposite to the angular movement of their respective rotors (I 3 and Il). In so doing, their peripheral rate of movement is approximately equal to the apparent peripheral velocity of the pistons K and L multiplied by the quantity' (i-Pr/Pc'), where Pr is equal to the periphery of the piston (K or L), and Pc is the periphery' of the circumscribed circle. In view of the limited and slow movement of bands 28 relative to casing I, it is feasible to construct the bands to flt'very closely against the cover plates 8 and 9 and thereby minimize leakage between the bands and such plates.

The rotary pistons K and L are so designed that at any angular position the sum of their radii along the line of centers of the shafts I I and I2 to the outer surfaces of the bands 26, 28 is` constant. For a, two-lobed rotor I have found that one mathematical expression which satisiles this principle is R=a+m sin2 W where R equals the radius to the surface of the band, a and m are constants, and W is the angle measured from the minor axis of the solid rotor This equation represents a curve having a deilnite relation to the periphery of the solid rotor. The curve representing the periphery of the solid rotor will be the inner envelope of a family of circles having a radius equal to the sum of the thickness,` of the ilexible band 26 and the diameter of the needle roller 21, and having their centers lying along the curve expressed by the equation above given.

4 The rotors I3 and I4, therefore, are of such the two rotary pistons K and L are always in contact with each other, and thus effectively preventing back ilow of fluid.

For a rotary piston having more than two lobes an especially desirable external contour is given by the expression R=a|m sin2 @2&0-

where R. equals the radius from the axis of rotation to the outer surface of the piston, a and m are constants, W is the angle measured from a rotors and roll on said cylindrical wall portions,v

the'reby forcing fluid trapped between the bands and said cylindrical wall portions from the inlet to the outlet.

2. A rotary pump comprising: .a casing, the casing including an internal cylindrical wall portion, cover plates, and an inlet and an outlet; an endless flexible band within said `cylindrical wall portion, the band being of a length less than the circumference of a circle coincident with said cylindrical wall portion and of a width substantially equal to the distance between the cover plates; a rotor free from the band having an axis coincident'with vthe axis of said cylindrical wall portion, the rotor including a cam. surface operative to press the flexible band against said cylindrical wall portion; friction-reducing means interposed between the cam surface and the band;

and a movable member between the inlet and the k outlet in continuous contact with said band,

,whereby rotation of said rotor causes the band Vwith said cylindrical wall portions, each rotor being enveloped by a free band which is flexible and stretchable; and antifriction means between 0 said rotors and their flexible bands, said bands being tensioned and urging said antifriction ymeans against the peripheries of said rotors, the

major axis of each--rotor with its enveloping flexible band being equal to the diameter of the surrounding cylindrical wall portion whereby the band is maintained in contact with such cylindrical wall portion, and the distance between the axes of rotation of said rotorsbeing such that the peripheries of the enveloping flexible bands are always in contact with each other; and said inlet and outlet being operatively separated by the rotors and their enveloping bands.

4. A rotary pump comprising: a iluid chamber having'an inlet and an outlet and two cylindrical Wall portions; quasi-elliptical rotors coaxial with said cylindrical wall portions, each rotor being enveloped by a free band which is flexible and stretchable; and antifriction rollers minor radius of the rotary piston, and n is 'the 65 number of lobes.

Having thus described my invention, I claim: l. A rotary pump comprising: a casing having an inlet and an outlet, a chamber in said easing in communication with the inlet and theoutlet and having cylindrical wall portions, pistons in said casing operatively separating the inlet from the outlet and mounted to rotate coaxially with said -cylindrical wall portions, said pistons being in continuous periphera1 contact with one another and with said cylindrical wall portions, each pis- 4 axes of rotation of said rotors being such that the peripheries of the enveloping bands are al- -ways in contact with each other; andv said inlet and outlet being operatively separated by the rotors and their enveloping bands.

5. A pump as defined yby claim 4 in which the flexible band-is of rubber or analogous material. 6. A rotary pump comprising: a iluid chamber 5 having two cylindrical wall portions and having an inlet and an'outlet; non-circular rotors coaxial with said cylindrical wall portions. each rotor being enveloped by a free flexible band which is movable relative thereto and assumes the non-circular shape thereof, and each band having a thin metala interior facing; and antifriction rollers between the facing and the rotor, said rotors with their enveloping bands constituting conjugate rotary pistons operating in said uid chamber.

7. In a rotary pump having a casing and conjugate'rotary pistons operatively engaging arcuate interior wall portions of, the casing, the iinprovement which comprises: each piston including a non-circular rotor portion, and an endless' flexible band portion enveloping the rotor portion and assuming the non-circular form thereof, said band portion progressing around the rotor as the rotor rotates and making rolling contact with one of said interior wall portions.

8. In a rotary pump having a casing and conjugate rotary pistons operatively engaging arcuate interior wall portions of the casing, the improvement which comprises: each piston including a non-circular rotor portion, an endless ilexible band portion enveloping the rotor portion and assuming the non-circular form thereof, and antifriction rolling bodies between said rotor portion and said band portion, said band portion progressing around the rotor as the rotor rotates and making rolling contact withone of said interior wall portions.

9. In a rotary pump having a casing and conjugate rotary pistons operatively engaging arcuate interior wall portions of the casing, the improvement which comprises: each piston including a quasi-elliptical rotor portion, and an endless band portion of rubber-like material enveloping the rotor portion and assuming the quasi-,elliptical form thereof, said band portion progressing around the rotor as the rotor rotates,

and making rolling contact with one of said interior wall portions.

10. In a rotary pump having a casing and conjugate rotary pistons operatively engaging arcuate interior wall portions of ,the casing, the improvement which comprises: each piston including a non-circular rotor portion, and an endless flexible band portion enveloping the rotor portion and assuming the non-circular form thereof,

lsaid band portion progressing around the rotor as the rotor rotates and making rolling contact with one of said wall portions, and said band portion being of rubber-like material with a metal interior facing.

11. In a rotary pump having a casing and conjugate rotary pistons operatively engaging arcuate interior wall portions of the casing, the improvement which comprises: each piston including a quasi-elliptical rotor portion, an endless iiexible band portion enveloping the rotor portion and assuming the quasi-elliptical form thereof, said band portion progressing around the rotor as the rotor rotates and making rolling contact with one of said wall portions, and said band portion being of rubber-like material with a metal interior facing; and rolling -bodies between said rotor portion and said facing.

12. In a rotary pump having conjugate rotary pistons, the improvement which comprises: each 4piston having an exterior surface the curve of which is l n,

R=a+fm sin W pistons, the improvement which comprises: each piston having an exterior surface the curve o! which is R=a+m sin? where R equals the radius from the axis ofrotation to the outer surface of the piston, a and m are constants, W is the angle measured from a minor radius of the rotary piston, and n is the number of lobes.

14. A rotary pump comprising: a casing having a chamber therein with a cylindrical wall portion and an inlet and outlet communicating with the chamber, a piston in said `chamber mounted to rotate coaxially with said cylindrical wall portion, said piston comprising a quasielliptical rotor with a free flexible band enveloping the same, the band being of uniform thickness to permit successive zones thereof to be pressed between the rotor and the cylindrical wall portion of the chamber, said band being free to progress around said rotor while rolling on said cylindrical wall portion, and movable means functionally interposed between the inlet and outlet and sealing between a wall of said chamber and said piston, whereby fluid is progressed by the piston from the inlet to the outlet.

15. A rotary pump comprising: a casing having a chamber therein with a cylindrical wall portion and an inlet and outlet communicating with the chamber, a piston in said chamber mounted to rotate coaxially with said cylindrical `wall portion, said piston comprising a non-circular rotor with a free flexible band enveloping the same, the band being of uniform thickness to permit successive zones thereof to be pressed b'etween the rotor and the cylindrical wall portion of the chamber, said band being free to progress around said rotor while rolling 'on said cylindrical wall portion, and movable means functionally interposed between the inlet and outlet and sealing between a wall of said chamber and said piston, whereby fluid is progressed by the p iston from the inlet to the outlet.

VIRGIL D.V BARKER.

REFERENCES CITED The following references` are of record in the file of this patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,451,603. October 19, 1948. VIRGIL D. BARKER It is hereby certified that errors appear 1n the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 37, for the Word including read includes; column 6, line 63, claim 4, for having read being;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent OHce.

Signed and sealed this 18th day of January, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uormn/asoner of Patents. 

